1. Field of the Invention
The present invention relates generally to railroad car truck brake systems, and more specifically, an adjustable brake beam.
2. Description of Related Art
Railroad car truck brake beams are well known in the art and provide a viable means of stopping a train. In FIG. 1, a conventional brake beam system 101 is shown. System 101 depicts a rectilinear compression member 103, a rectilinear tension member 129, strut 117 with means for connecting said tension member 129 and said compression member 103, brake heads 131 and 133 with recesses so that said tension member 129 and said compression member 103 may be partially located therein.
As depicted in FIG. 1, a brake beam system 101 is supported on guides 127 and 109 located adjacent to the wheels 105 and 123. A lever (not shown) inserted within the slot 121 applies force in the direction of arrows 113 and 115. When force is applied in the direction of arrow 113, the beam 103 moves in the direction arrow 113 so that brake shoes 125 and 107 contact wheels 123 and 105, respectively.
As is known to those skilled in the art, because of the substantial speeds at which railroad cars travel and the heavy loads they carry, large braking forces are required to be transferred to the wheels through the brake beam assemblies during their operation. These forces, and random vibrations borne through the truck structure to the brake beams, create stresses in numerous areas.
The rails 109 and 127 contain recessed, parallel side pockets with an internal liner (not shown in FIG. 1 but discussed in more detail herein) which allow the beam 103 to move by sliding in directions 113 and 115. The brake heads 131 and 133 contain protrusions 135 and 137, respectively, which are commonly known as end extensions. The end extensions 135 and 137 are tapered by design and are sized to fit into the side pockets of the rails 109 and 127. It is notable that the end extensions 135 and 137 are non-adjustably integral to the brake heads 131 and 133, respectively, since the brake heads (with end extensions) are manufactured as a “one piece” casting. As depicted in FIG. 1, each brake beam system 101 contains a right hand and left hand brake head.
When the brake beam 103 is engaged such that the brake shoes 125 and 107 contact the wheels 123 and 105, the resultant friction force is transmitted through the brake beam system 101 through end extensions 135 and 137 to the fixed rails 127 and 109. Due to tolerance stack-up and loose regulatory standards, the end extensions 135 and 137 loosely fit in the side pockets of the rails 127 and 109 causing them to become diagonally constrained when the brake beam is engaged. Simply put, the end extensions 135 and 137 contact the side pockets via two-point contact; one point on the upper trailing edge of the side pocket and another point on the lower leading edge of the side pocket.
The inherent sloppy fit of the tapered end extensions 135 and 137 to the side pockets of the rails 127 and 109 allows the brake beam to move until the end extensions become diagonally constrained. This allowable, inherent movement causes misalignment between brake shoes 107 and 125 and wheels 105 and 123 resulting in uneven brake shoe wear. This uneven shoe wear; commonly referred to as shoe taper, can occur on new railcars during the first deployment of use. This is viewed as a disadvantage of conventional brake beam systems.
Although great strides have been made in the area of brake beam system, many shortcomings remain.
While the system and method of use of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present application as defined by the appended claims.